This is the largest of all the Locustella warblers, approaching the size of the great reed warbler. The adult has an unstreaked olive-brown back, uniformly grey breast and buff underparts, with unmottled dull orange under tail-coverts.

The song is a short phrase, loud and distinctive; nothing like the insect-like reeling of European Locustella species, and more musical than that of Pallas's grasshopper warbler.